Supercharging of internal combustion engines is a well established method of obtaining greater power output from engines of a given size. Due to the extremely high rotational speeds of the compressor, gears, bearing races, and other moving parts of superchargers, it is imperative to maintain adequate lubrication in superchargers. In addition to preventing excessive wear of parts, lubrication aids in cooling of the parts.
In present superchargers, lubrication slingers are commonly used to provide lubrication to the moving part. See for example U.S. Pat. No. 5,638,796 to Adams, III et al., which discloses an electric supercharger with a lubrication slinger, and U.S. Pat. No. 4,171,137 to Aizu et al., which discloses a slinger arrangement for use with the bearing of superchargers. Others indicate, in a general manner, that some oil will be kicked up by the slinging and create an oil mist that will tend to provide some lubrication. See for example U.S. Pat. No. 5,281,116 to Gwin, U.S. Pat. No. 5,241,932 to Everts, U.S. Pat. No. 4,423,710 to Williams, and U.S. Pat. No. 5,579,735 to Todero et al. U.S. Pat. No. 4,752,193 to Horler discloses using the venturi effect created by a turbocharger to aid in evacuating oil that collects at the bottom of the supercharger's gear case.
U.S. Pat. No. 5,375,573 to Bowman disclosing a two-stroke internal combustion engine having a pressurized air rail. The pressurized air rail is for producing an atomized fuel spray for injection into the individual combustion chambers, in which oil for lubrication is atomized by metering it into a stream of compressed air taken from the rail or a reservoir connected thereto and the resulting oil/air mist is injected into the crankcase and/or the lower part of the cylinder selectively and directly onto points requiring lubrication. Bowman discloses that to reduce the load on the air compressor feeding the pressurizing rail, the compressed air supply for the oil atomization may be supplemented by an engine supercharger, if one is utilized. Bowman further states that each cylinder of the engine is provided with a plurality of lubricating jets or nozzles to generally direct atomized oil locally to easily accessible parts and components in a two stroke engine such as the small-end bearings, big-end bearings, the piston skirt and piston ring areas. Bowman does not disclose use of a misting oil/air system for lubricating supercharger bearings, or using a misting oil/air system for lubricating less accessible components such as bearing races press fitted into bearing race cavities in superchargers.
Superchargers are frequently belt driven and have gears in a gear case to substantially gear up the rotational speed so that the compressor of the supercharger will generate sufficient boost. In presently available superchargers, the space inside the gear case is purposely made relatively large, with much space between the gears and the walls of the gear case so that oil can be flung onto the various gears and bearings. However, one side effect of large cases is that oil that accumulates in the bottom of the case to be drained is sometimes whipped up by the gears and become foamy. This foamed oil hinders drainage, and as a result the oil will increase in temperature, and lower the performance of the supercharger.
Although there has been a substantial amount of development work on more efficient designs for superchargers, there remains a need for improved superchargers that are more compact in design, are better lubricated, and that are more durable, more efficient, and readily installable onto different engines.